meet in their first presidential debate. the news hour's jim lehrer moderates from the university of denver. watch and engage with crmbing span including our live debate preview at 7:00 p.m. eastern, the debate at 9:00 and post-debate your reactions. follow on c-span, c-span radio and online at c-span.org. >> september 11, 2001, was a day that change midlife forever. it changed america's life. i'm going to go through a power point presentation which is going to outline the account of the historical account of the attack as things happened, as things transpyred that day. it gets -- transpired that day. et gets intense. i'm going to do my best not to ramble on and go too fast. i would ask you to sit back, leer your mind, put yourself in that room an you'll get a real sense of what it was like to be at the too much the food chain, the national command authority, as a nation of 300 million americans was attack by 19 al qaeda terrorists. >> more from retired lieutenant colonel robert darling inside the president's bunker, this we